In this question I answered "éramos" instead of "fuimos" since the text referred to "used to be." Why was that wrong? I get that the "completed action in the past" hint confused the situation. Shouldn't the question be clarified, or am I missing something here?
Nosotros ________ muy buenos estudiantes.We used to be very good students.(HINT: Refers to a completed action in the past.)
From the lesson:
"Note that while "fue" is generally translated into "was" in English, "era" can be translated into "was", "used to be" and "would be"."